The present invention relates to a method of preparing, for the driver of a vehicle, route guide information which is to be given in the form of instructions for turning the vehicle at various points along the route, the method employing a stored street map, wherein a route leading over guide points to a destination is established for the driver of the vehicle as the intended route.
Various methods and devices have become known for the guiding of a motor vehicle to its destination. In this connection, after the determination of the desired route to be taken, route guide information is transmitted during vehicular travel to the driver of the vehicle. This may involve, for instance, a change in direction (turn) at a coming intersection or junction being indicated on a display device (display). In addition to or instead of an optical display, a spoken command can also be provided, for instance in the form "turn right" or "turn left".
In order that an associating of the display or vocal command with the corresponding route guide point is possible, the display is presented at a point in time corresponding to a predetermined distance before the route turn point, for instance 200 meters. This distance is determined by a comparison between the position of the route turn point and the position of the vehicle as determined in each case by a location detector. The determination of the position in the past, however, has been subject to tolerances of, for instance, 100 meters so that in the case of a relatively late display the driver will possibly no longer be able to react and in the case of too early a display the driver may turn into a cross street before the route turn point.